1. Field of the Invention
This invention relates to packaging for electronic circuitry and more particularly to housings for packaging electronic equipment.
2. Background of the Invention
In the prior art, electronic computer circuitry and equipment have typically been packaged in metal housings or enclosures, different sides or panels of which are removable to gain access to the circuits and equipment in the interior of the housing. Alternatively, an entire housing cover is removed as a single piece from the top of the equipment housing to gain access to the circuits and other equipment inside.
Power and signal cables to and between a group of housings in a computer system typically connect to connectors mounted at the rear of the housings. Various switches are also located on the rear of the housings. Access to and removal of printed circuit (PC) cards and other modules such as power supplies, disk drives, and fans are typically achieved by the removal of a front panel of such housings.
There are many shortcomings with these prior art electronic equipment housings. For example, the rear housing cabling arrangement normally requires that the housings be spaced far enough from a wall to provide room for the cables, and so that access may be had to the cables and switches at the rear of the housings. This creates unused floor space that can add to certain inefficiencies. In addition, the cables normally situated on the floor behind the housings create certain hazards. The problem is made worse by the fact that the cables are usually made to a standard length and typically too long, thus requiring that the excess cabling be coiled or just lie in disarray.
To minimize the wasted floor space, the equipment is sometimes located as close to the wall as possible. This has been found to create another problem of access to the cables and their connectors, switches and even the rear of housing accessed interior components. In such arrangements, to gain working access to the rear of the housings, the equipment must be temporarily moved further away from the wall which often creates other problems such as inadvertently disconnecting and/or damaging connectors.
Access to printed circuit cards and other equipment through the front of a housing may be accomplished by removing its front panel if the housing is relatively high so that the interior can be accessed by a person while standing up. However, many modern housings are only two to three feet high. The result is that a person must assume a prone position to view the interior of the housing and to remove printed circuit cards and other modules therefrom. This has been found to be both inefficient and inconvenient.
Another problem with some prior art housings is that printed circuit cards containing temperature sensitive components are sometimes mounted adjacent to heat generating equipment such as power supplies. Thus, the same cooling air is circulated over the printed circuit cards and the high heat generating component such as the power supplies. Where the air passes over the printed circuit cards first, the air is warmed before reaching components such as power supplies resulting in decreased cooling effect. To compensate for such cooling inefficiencies, either larger fans are used which require more space and use more power, or the maximum temperature of the room in which the equipment is located is lowered.
Thus, there is a need in the prior art for an electronic equipment housing which can be located close to a wall to conserve floor space. In addition, there is a need for a way to more conveniently access printed circuit cards and most other equipment in the housing. Moreover, there is a need for a cabling arrangement which can minimize exterior cabling which still permits the use of standard length cables. Further, there is a need for an equipment arrangement in the housings that permits adequate cooling via convection and with the smallest possible cooling fans.